Array of thin film actuated mirrors for use in an optical projection system and method for the manufacture thereof

ABSTRACT

An array of M×N thin film actuated mirrors for use in an optical projection system comprises an active matrix, an array of M×N thin film actuating structures, each of the thin film actuating structures being provided with a first and a second actuating parts, each of the first and second actuating parts including at least a thin film layer of a motion-inducing material, a pair of electrodes, each of the electrodes being provided on top and bottom of the motion-inducing thin film layer, an array of M×N supporting members, each of the supporting members being used for holding each of the actuating structures in place by cantilevering each of the actuating structures and also for electrically connecting each of the actuating structures and the active matrix, and an array of M×N mirror layers for reflecting light beams, each of the mirror layers further including a first side, a second opposing side and a center portion located therebetween, wherein the first side and the second opposited side of each of the mirror layers are secured on top of the first and second actuating parts of each of the actuating structures, respectively, such that when the first and second actuating parts in each of the actuating structures deform in response to an electrical signal applied between the first and second electrodes, the center portion of the corresponding mirror layer tilts while remaining planar, thereby allowing all of the center portion to reflect the light beams, resulting in an increased optical efficiency.

FIELD OF THE INVENTION

The present invention relates to an optical projection system; and, moreparticularly, to an array of M×N thin film actuated mirrors for use inthe system and method for the manufacture thereof.

DESCRIPTION OF THE PRIOR ART

Among the various video display systems available in the art, an opticalprojection system is known to be capable of providing a high qualitydisplay in a large scale. In such an optical projection system, lightfrom a lamp is uniformly illuminated onto an array of, e.g., M×N,actuated mirrors such that each of the mirrors is coupled with each ofthe actuators. The actuators may be made of an electrodisplacivematerial such as a piezoelectric or an electrostrictive material whichdeforms in response to an electric field applied thereto.

The reflected light beam from each of the mirrors is incident upon anaperture of a baffle. By applying an electrical signal to each of theactuators, the relative position of each of the mirrors to the incidentlight beam is altered, thereby causing a deviation in the optical pathof the reflected beam from each of the mirrors. As the optical path ofeach of the reflected beams is varied, the amount of light reflectedfrom each of the mirrors which passes through the aperture is changed,thereby modulating the intensity of the beam. The modulated beamsthrough the aperture are transmitted onto a projection screen via anappropriate optical device such as a projection lens, to thereby displayan image thereon.

In FIG. 1, there is shown a cross sectional view of an M×Nelectrodisplacive actuated mirror array 10 for use in an opticalprojection system, disclosed in a copending commonly owned application,U.S. Ser. No. 08/278,472, U.S. Pat. No. 5,735,026 entitled"ELECTRODISPLACIVE ACTUATED MIRROR ARRAY, comprising: an active matrix11 including a substrate 12 and an array of M×N transistors thereon; anarray 13 of M×N electrodisplacive actuators 30, each of theelectrodisplacive actuators 30 including a pair of actuating members 14,15, a pair of bias electrodes 16, 17, and a common signal electrode 18;an array 19 of M×N hinges 31, each of the hinges 31 fitted in each ofthe electrodisplacive actuators 30; an array 20 of M×N connectingterminals 22, each of the connecting terminals 22 being used forelectrically connecting each of the signal electrodes 18 with the activematrix 11; and an array 21 of M×N mirrors 23, each of the mirrors 23being mounted on top of each of the M×N hinges 31.

There is a number of problems associated with the above describedelectrodisplacive actuated mirror array. First of all, since theelectrodisplacive material making up the actuating members is in a bulkform, it will likely degrade after an extended use, which will in turnaffect the performance of the actuated mirrors in the array.Furthermore, since each of the actuated mirrors is not separated fromeach other, electrically or physically, the action of each actuatedmirror is affected by those of the neighboring actuated mirrors.

In the above mentioned copending, commonly owned application, there isalso disclosed a method for manufacturing such an array of M×Nelectrodisplacive actuated mirrors, employing a ceramic wafer having athickness of 30 to 50 μm.

There is room for further improvements over the above described methodfor manufacturing an array of M×N electrodisplacive actuators, however.First of all, it is rather difficult to obtain a ceramic wafer having athickness of 30 to 50 μm; and, furthermore, once the thickness of theceramic wafer is reduced to a 30 to 50 μm range, the mechanicalproperties thereof are likely to degrade which may, in turn, make itdifficult to carry out the manufacturing process.

In addition, it involves a number of time consuming, hard to control,and tedious processes, thereby making it difficult to obtain the desiredreproducibility, reliability and yield; and, furthermore, there may be alimit to the down sizing thereof.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of the present invention is toprovide a method for manufacturing an array of M×N actuated mirrors,which dispenses with the use of a thin electrodisplacive ceramic wafer.

It is another object of the present invention to provide an improved andnovel method for manufacturing an array of M×N actuated mirrors whichwill give higher reproducibility, reliability and yield.

It is a further object of the present invention to provide an array ofM×N actuated mirrors having a novel structure and capable of maintaininga performance integrity after an extended use.

It is a still another object of the present invention to provide anarray of M×N actuated mirrors having an improved optical efficiency.

In accordance with one aspect of the present invention, there isprovided an array of M×N thin film actuated mirrors for use in anoptical projection system, the array comprising: an active matrixincluding a substrate, an array of M×N transistors and an array of M×Nconnecting terminals; an array of M×N thin film actuating structures,each of the actuating structures including a first and a secondactuating parts, the first and second actuating parts being identicallystructured, each of the first and second actuating parts being providedwith a top and a bottom surfaces, a proximal and a distal ends, each ofthe first and second actuating parts having at least a thin film layerof a motion-inducing material including a top and a bottom surfaces anda first and a second electrode with the first electrode being placed onthe top surface of the motion-inducing thin film layer, and the secondelectrode, on the bottom surface of the motion-inducing thin film layer,wherein an electrical signal applied across the motion-inducing thinfilm layer between the first and second electrodes of each actuatingpart causes a deformation of the motion-inducing thin film layer, andhence the actuating part; an array of M×N supporting members, each ofthe supporting members being provided with a top and a bottom surfaces,wherein each of the supporting members is used for holding each of theactuating structures in place and also for electrically connecting eachof the actuating structures with the active matrix; and an array of M×Nmirror layers, each of the mirror layers including a mirror forreflecting light beams and a supporting layer, each of the mirror layersfurther including a first side, a second opposing side and a centerportion located therebetween, wherein the first side and the secondopposing side of each of the mirror layers are secured on top of thefirst and second actuating parts of each of the actuating structures,respectively, such that when the first and second actuating parts ineach of the actuating structures deform in response to the electricalsignal, the center portion of the corresponding mirror layer tilts whileremaining planar, thereby allowing all of the center portion to reflectthe light beams, resulting in an increased optical efficiency.

In accordance with another aspect of the present invention, there isprovided a novel method for manufacturing an array of M×N actuatedmirrors for use in an optical projection system, utilizing the knownthin film techniques, the method comprising the steps of: (a) providingan active matrix having a top and a bottom surfaces, the active matrixincluding a substrate, an array of M×N transistors and an array of M×Nconnecting terminals; (b) forming a first supporting layer on the topsurface of the active matrix, the first supporting layer including anarray of M×N pedestals corresponding to the array of M×N supportingmembers in the array of M×N thin film actuated mirrors and a firstsacrificial area; (c) treating the first sacrificial area of the firstsupporting layer to be removable; (d) depositing a first thin filmelectrode layer on the first supporting layer; (e) providing a thin filmmotion-inducing layer on the first thin film electrode layer; (f)forming a second thin film electrode layer on the thin filmmotion-inducing layer; (g)patterning the first thin film electrodelayer, the thin film motion-inducing layer and the second thin filmelectrode layer into an array of M×N actuating structures and an emptyarea surrounding thereof, each of the actuating structures furtherincluding a first and a second actuating parts; (h) forming secondsacrificial layer on the empty area surrounding each of the actuatingstructures; (i)treating the second sacrificial layer to be removable;(j) patterning the second sacrificial layer into an array of M×Nsacrificial members; (k) depositing a second supporting layer on top ofthe array of M×N actuating structures and the second sacrificial layerpatterned in the previous step; (l)depositing a light reflecting layeron top of the second supporting layer; (m) pattering the lightreflecting layer and the second supporting layer into an array of M×Nmirror layers; and (n) removing the first sacrificial areas and thearray of M×N sacrificial members to thereby form said array of M×N thinfilm actuated mirrors.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodimentsgiven in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a cross sectional view of an array of M×N electrodisplaciveactuated mirrors previously disclosed;

FIG. 2 represents a cross sectional view of M×N thin film actuatedmirrors in accordance with the first preferred embodiment of the presentinvention;

FIG. 3 illustrates a detailed cross sectional view of the inventive thinfilm actuated mirror array of the first embodiment, shown in FIG. 2;

FIG. 4 depicts a top view of the inventive thin film actuated mirrorarray of the first embodiment, shown in FIG. 2;

FIG. 5 presents a detailed perspective view of the inventive thin filmactuated mirror array of the first embodiment, shown in FIG. 2;

FIG. 6 offers another possible mirror layer configuration for the firstembodiment;

FIG. 7 discloses a cross sectional view of a thin film actuated mirrorof the first embodiment in an actuated state;

FIG. 8 provides a cross sectional view of a thin film actuated mirror ofthe second embodiment having a bimorph structure;

FIG. 9 is a cross sectional view of an array of M×N thin film actuatedmirrors in accordance with the third preferred embodiment of the presentinvention;

FIG. 10 displays a detailed cross sectional view of the inventive thinfilm actuated mirror array of the third embodiment, shown in FIG. 9;

FIG. 11 describes a perspective view of the inventive thin film actuatedmirror array of the third embodiment, shown in FIG. 9; and

FIGS. 12A to 12J reproduce schematic cross sectional views setting forththe manufacturing steps for the first embodiment in accordance with theresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 2 to 12, there are provided schematic crosssectional views of the inventive array of M×N thin film actuated mirrorsfor use in an optical projection system and method for the manufacturethereof, wherein M and N are integers, in accordance with preferredembodiments of the present invention. It should by noted that like partsappearing in FIGS. 2 to 12 are represented by like reference numerals.

In FIG. 2, there is illustrated a cross sectional view of a firstembodiment of an array 50 of M×N thin film actuated mirrors 51,comprising an active matrix 52, an array 53 of M×N thin film actuatingstructures 54, an array 55 of M×N supporting members 56, and an array 57of M×N mirror layers 58.

FIG. 3 represents a detailed cross sectional view of the thin filmactuated mirror array 50, shown in FIG. 2. The active matrix 52 includesa substrate 59, an array of M×N transistors (not shown) and an array 60of M×N connecting terminals 61. Each of the actuating structures 54includes identically structured first actuating and second actuatingparts 62(a), 62(b), wherein each actuating part, e.g., 62(a), isprovided with a top and a bottom surfaces 63, 64, a proximal and adistal ends 65, 66. Each actuating part, e.g., 62(a), further has atleast a thin film layer 67 of a motion-inducing material, e.g., apiezoelectric material, an electrostrictive material or amagnetostrictive material, including a top and a bottom surface 68, 69and a first and a second electrodes 70, 71 with the first electrode 70being placed on the top surface 68 of the motion-inducing layer 67 andthe second electrode 71, on the bottom surface 71 of the motion-inducinglayer 67. In the case when the motion-inducing layer 67 is made of apiezoelectric material., e.g., lead zirconium titanate(PZT), it must bepoled. The first and second electrodes are made of a metal such asgold(Au) or silver (Ag).

Each of the M×N supporting members 56, provided with a top and bottomsurfaces 72, 73, is used for holding the first and the second actuatingparts 62(a), 62(b) of each of the actuating structures 54 in place andalso for electrically connecting the second electrode 71 in the firstand second actuating parts 62(a), 62(b) in each of actuating structures54 with the corresponding connecting terminal 61 on the active matrix 52by being provided with a conduit 99 made of an electrically conductivematerial, e.g., a metal. In this inventive array 50 of M×N thin filmactuated mirrors 51, each of the first and second actuating parts 62(a),62(b) in each of the actuating structures 54 are cantilevered from eachof the supporting members 56 by being mounted on the top surface 73 ofeach of the supporting members 56 at the bottom surface 64 of each ofthe first and second actuating parts 62(a), 62(b) in each of theactuating structures 54 at the proximal end 65 thereof, and the bottomsurface 74 of each of the supporting members 56 is placed on top of theactive matrix 52.

Furthermore, each of the mirror layer 58, including a mirror 75 forreflecting light beams and a supporting layer 76 having a top surface77, is provided with a first side 78, a second opposing side 79 and acenter portion 80 located therebetween, as illustrated in FIG. 4. Thefirst side 78 and the second opposing side 79 of each of the mirrorlayers 58 are placed on top of the first and second actuating parts62(a), 62(b) of each of the actuating structures 54, respectively.

When an electric field is applied across the motion-inducing layer 67between the first and second electrodes 70, 71, of each actuating parts62(a), 62(b) in each of the actuating structures 54, the motion-inducinglayer 67 thereof will deform, which will, in turn, cause a deformationof the first side 78 and second opposing sides 79 of the correspondingmirror layer 58. In such a situation, the center portion 80 of thecorresponding mirror layer 58, unlike the first side 78 and the secondopposing sides 79, will not deform, i.e, it will remain planar,resulting in an increased optical efficiency. In FIGS. 5 and 6, thereare shown a perspective view of a thin film actuated mirror 51 of thefirst embodiment and another possible mirror layer configuration for thearray 50 of M×N thin film actuated mirrors 51, respectively.

The material making up the supporting layer 76 in each of the mirrorlayers 58 can be also light reflecting, e.g., aluminum (A1), which willallow the top surface 77 thereof to function also as the mirror 75 ineach of the thin film actuated mirrors 51.

It is possible for the inventive array 50 of thin film actuated mirrors51 to function equally well by having the top and bottom surfaces 68, 69of the motion-inducing thin film layer 67 in each of the actuatingstructures 54 covered completely with the first and second electrodes70, 71 or by having either one of the top and bottom surfaces 68, 69 ofthe motion-inducing thin film layer 67 in each of the actuatingstructures 54 covered partially with the first and second electrodes 70,71.

By way of example of the first embodiment, there are illustrated inFIGS. 3 and 7 an array 50 of M×N thin film actuated mirrors 51comprising an array 53 of M×N actuating structures 54, made of apiezoelectric material, e.g., PZT. An electric field is applied acrossthe piezoelectric thin film layer 67 located between the first andsecond electrodes 70, 71 in each of the actuating parts 62(a), 62(b) ineach of the actuating structures 54. The application of the electricfield will either cause the piezoelectric material to contract orexpand, depending on the polarity of the electric field with respect tothe poling of the piezoelectric material. If the polarity of theelectric field corresponds to the polarity of the piezoelectricmaterial, the piezoelectric material will contract. If the polarity ofthe electric field is opposite the polarity of the piezoelectricmaterial, the piezoelectric material will expand.

In FIG. 7, the polarity of the piezoelectric material corresponds to thepolarity of the applied electric field, causing the piezoelectricmaterial to contract. In such a case, the first and second actuatingparts 62(a), 62(b) of each of actuating structure 54 bend downward, asshown in FIG. 7, thereby tilting the first side 78 and the secondopposing side 79 of the mirror layer 58 downward at an angle. The centerportion 80 of the mirror layer 58, however, remains planar, and as aresult, the effective length of the mirror layer 58 is the entire lengthof the center portion 80 of the mirror layer 58. In comparison, if themirror layer 58 is directly secured to the actuating structure 54, theportion of the mirror layer 58 secured to the supporting member 56 doesnot deform in reaction to the electric field, but remains securely inplace. As a result, the effective length of the mirror layer 58 is equalto a length less the length of the portion of the actuating structure 54secured to the supporting member 56. The implementation of the firstside 78, the second opposing side 79 and the first and second actuatingparts 62(a), 62(b) attached thereto, respectively, in the firstembodiment shown in FIG. 3, therefore, increases the fill factor andefficiency of the array 57 of mirror layers 58. Referring now to FIGS. 3and 7, it can be shown that the light impinging on the mirror layer 58,of the actuated mirror 51 shown in FIG. 7 is deflected at a larger anglethan the light reflected from of the unactuated actuated mirror 51 shownin FIG. 3.

Alternatively, an electric field of a reverse polarity may be appliedacross the motion-inducing thin film piezoelectric layer 67, causing thepiezoelectric material to expand. In this example, the actuatingstructure 54 bends upward(not shown). The light impinging the mirrorlayer 58 of the upwardly actuated mirror 51 is deflected at a smallerangle than the light deflected from the unactuated actuated mirror 51shown in FIG. 3.

There is shown in FIG. 8 a cross sectional view of a second embodimentof an array 100 of M×N thin film actuated mirrors 101, wherein thesecond embodiment is similar to the first embodiment except that each ofthe first and second actuating parts 62(a), 62(b) in each of theactuating structures 54 is of a bimorph structure, including a firstelectrode 70, a second electrode 71, an intermediate metal layers 87 anupper motion-inducing thin film layer 89 having a top and a bottomsurfaces 90, 91 and a lower motion-inducing thin film layer 92 providedwith a top and bottom surfaces 93, 94. In each of the actuating parts62(a), 62(b), the upper and lower motion-inducing thin film layers 89,92are separated by the intermediate metal layer 87, the first electrode 70being placed on the top surface 90 of the upper motion-inducing thinfilm layer 89, and the second electrode 71, on the bottom surface 94 ofthe lower motion-inducing thin film layer 92.

As in the case of the first embodiment, the upper and lowermotion-inducing thin film layers 89, 92 in each of the actuatingstructures 54 are made of a piezoelectric material, an electrostrictiveceramic or a magnetostrictive ceramic. In the case when the upper andlower motion-inducing thin film layers 89,92 are made of a piezoelectricmaterial, e.g., a piezoelectric ceramic or a piezoelectric polymer, theupper and lower motion-inducing thin film layers 89,92 must be poled insuch a way that the polarization direction of piezoelectric material inthe upper motion-inducing thin film layer 89 is opposite from that ofthe lower motion-inducing thin film layer 92.

As an example of how the second embodiment functions, assume that theupper and lower motion-inducing layers 89, 90 in the array 100 of M×Nthin film actuated mirrors 101 shown in FIG. 8 are made of apiezoelectric material, e.g., PZT. When an electric field is appliedacross each of the actuating structures 54, the upper and lowermotion-inducing thin film piezoelectric layers 89, 92, of the actuatingstructure 54 will either bend upward or downward, depending on thepoling of the piezoelectric material and the polarity of the electricfield. For example, if the polarity causes the upper motion-inducingthin film piezoelectric layer 89 to contract, and the lowermotion-inducing thin film piezoelectric layer 92 to expand, theactuating parts 62(a), 62(b) in each of the actuating structures 54 willbend upward. In this situation, the impinging light is deflected at asmaller angle from the actuated mirror 51 than the deflected light fromthe unactuated actuated mirror 51. However, if the polarity of thepiezoelectric material and the electric field causes the uppermotion-inducing thin film piezoelectric layer 89 to expand and the lowermotion-inducing thin film piezoelectric layer 92 to contract, theactuating structure 54 will bend downward. In this situation, theimpinging light is deflected at a larger angle from the actuated mirror51 than the deflected light from the unactuated actuated mirror 51.

There are illustrated in FIG. 9 a schematic cross sectional view of athird embodiment of an array 200 of M×N thin film actuated mirrors 201.The third embodiment is similar to the first embodiment except that thefirst and second actuating parts 62(a), 62(b) of each of the actuatingstructures 54 lack the supporting layer 76 in the mirror layer 58.Instead, they are provided with an elastic layer 202 located on thebottom surface 69 of the motion-inducing layer 67, as shown in FIG. 10.Conventionally, when an elastic layer is provided in an actuated mirror,the motion-inducing and elastic layers are usually separated by a layerof an expensive electrically conducting metal, e.g., platinum (Pt) toimprove adhesion therebetween.

However, if the thermal expansion coefficient of the materials making upthe elastic layer and the motion-inducing layer is drastically differenteach other and the interface between the elastic layer and theelectrically conductive metal layer or the interface between themotion-inducing layer and the electrically conductive layer are weak,they will lead to a peeling of the electrically conductive metal layer,thereby reducing the overall performance of the actuated mirror. Apossible solution to this problem is to form the elastic andmotion-inducing layers with the materials having the same structure,e.g., perovskite. Since the materials making up the elastic andmotion-inducing layers are similar structurally, it will betteradhesivity therebetween to thereby eliminate the need for forming of theelectrically conductive metal layer and also allow an easier control ofstrain energy therebetween. One possible combination of the suchmaterials are PZT for the motion-inducing layer and leadtitanate(PbTiO₃) for the elastic layer. In this case, the materialmaking up the elastic layer is characterized by a high dielectricconstant(.di-elect cons.) and a low piezoelectric constant(d).

Also, if the first electrode is made of a light reflecting material.e.g., A1, the mirror layer 58 can be omitted. In such a case the firstelectrode will also function as the mirror layer 58.

There are illustrated in FIGS. 12A to 12J the manufacturing stepsinvolved in manufacturing of the first embodiment of the presentinvention. The process for manufacturing the first embodiment, i.e., thearray 50 of M×N thin film actuated mirror 51, wherein M×N are integers,begins with the preparation of the active matrix 52, having the top anda bottom surfaces 102, 103, comprising the substrate 59, the array ofM×N transistors (not shown) and the array 104 of M×N connectingterminals 105, as illustrated in FIG. 12A.

In the subsequent step, there is formed on the top surface 102 of theactive matrix 52 a first supporting layer 106, including an array 107 ofM×N pedestals 108 corresponding to the array 55 of M×N supportingmembers 56 and a first sacrificial area 109, wherein the firstsupporting layer 106 is formed by: depositing a first sacrificial layer(not shown) on the entirety of the top surface 102 of the active matrix52; forming an array of M×N empty slots (not shown), to therebygenerated the first sacrificial area 109, each of the empty slots beinglocated around each of the M×N connecting terminals 61; and providing apedestal 108 in each of the empty slots, as shown in FIG. 12B. The firstsacrificial layer is formed by using a sputtering method, the array ofempty slots, using an etching method, and the pedestals, using asputtering or a chemical vapor deposition(CVD) method, followed by anetching method. The sacrificial area 109 of the first supporting layer106 is then treated so as to be removable later using an etching methodor the application of chemicals.

A conduit 99 for electrically connecting each of the connectingterminals 62 with each of the second electrode 71, made of anelectrically conductive material, e.g., tungsten(W), is formed in eachof the pedestals 108 by first creating a hole extending from top thereofto top of the corresponding connecting terminal 61 using an etchingmethod, followed by filling therein with the electrically conductingmaterial, as depicted in FIG. 12C.

In the subsequent step, as depicted in FIG. 12D, a first thin filmelectrode layer 111, made of an electrically conducting material, e.g.,Au, is deposited on the first supporting layer 106. Thereafter, a thinfilm motion-inducing layer 112, made of a motion-inducing material,e.g., PZT, and a second thin film electrode layer 113 are then formed onthe first thin film electrode layer 111.

Thereafter, the first thin film electrode layer 111, the thin filmmotion-inducing layer 112 and the second thin film electrode layer 113are patterned into an array 53 of M×N actuating structures 54 and anempty area(not shown) surrounding each of the actuating structures 54,wherein each of the actuating structures 54 includes the first andsecond actuating parts 62(a), 62(b), as shown in FIG. 12E.

Subsequently, a second sacrificial layer 114 is formed on the empty areasurrounding each of the actuating structures 54, as described in FIG.12F. The second sacrificial layer 114 is then treated so as to beremovable later.

As depicted in FIG. 12G, the sacrificial layer 114 is then patternedinto an array 115 of M×N sacrificial members 116. Subsequently a secondsupporting layer 117 and a light reflecting layer 119 comprising themirror layer 58 are successively deposited on top of the array 53 of M×Nactuating structures 54 and the second sacrificial layer 116 patternedpreviously, as illustrated in FIG. 12H.

The light reflecting layer 119 and the second supporting layer 117 arethen patterned into an array 57 of M×N mirror layers 58, as depicted inFIG. 121.

The thin film layers of the electrically conducting, themotion-inducing, and the light reflecting materials may be deposited andpatterned with the known thin film techniques, such as sputtering,sol-gel, evaporation, etching and micro-machining.

Thereafter, the first sacrificial area 109 and the array 115 of M×Nsacrificial members 116 are then removed or dissolved by the applicationof chemical to thereby form said array 50 of M×N thin film actuatedmirrors 51, as depicted in FIG. 12J.

The fabrication of the second embodiment is similar to that of the firstembodiment except that it requires two additional steps, the additionalsteps being the formation of an additional motion-inducing layer and anintermediate metal layer.

In the case of the third embodiment, since each of the first and secondactuating parts 62(a), 62(b) in each of the actuating structures 54 isprovided with an elastic layer 202 on the bottom surface of the motioninducing layer 67 while missing the supporting layer 76, themanufacturing step for the third embodiment are essentially the same asthose of the first embodiment with the orders being changed slightly.Furthermore, if the second electrode layer is made of a light reflectingmaterial, e.g., A1, the step involved in forming of the light reflectinglayer 119 can also be omitted form the overall manufacturing steps.

While the present invention has been described with respect to certainpreferred embodiments only, other modifications and variations may bemade without departing from the scope of the present invention as setforth in the following claims.

What is claimed is:
 1. An array of M×N thin film actuated mirrors foruse in an optical projection system, the array comprising:an activematrix including a substrate and an array of M×N connecting terminals;an array of M×N thin film actuating structures, each of the actuatingstructures including a first and a second actuating parts, each of thefirst and second actuating parts being provided with a proximal and adistal ends, each of the actuating parts having at least a thin filmlayer of motion-inducing material and a first electrode and a secondelectrode with the first electrode being placed on top of themotion-inducing thin film layer, and the second electrode, at bottom ofthe motion-inducing thin film layer, wherein an electrical signalapplied across the motion-inducing thin film layer between the first andsecond electrodes of each actuating part causes a deformation of themotion-inducing thin film layer of the actuating part; an array of M×Nsupporting members, wherein the first and second actuating parts arecantilevered from each of the supporting members and wherein each of thesupporting member is provided with a conduit for electrically connectingeach of the actuating structures with the active matrix; and an array ofM×N mirror layers, adapted for reflecting light beams, each of themirror layers including a first side portion, a second opposing sideportion and a center portion located therebetween, said first sideportion having a first side edge remote from said center portion and asecond side edge adjacent a respective side edge of said center portion,said second opposing side portion having a first side edge remote fromsaid center portion and a second side edge adjacent a respective sideedge of said center portion, wherein the first side portion and thesecond opposing side portion of each of the mirror layers are secured ontop of the first and second actuating parts of each of the actuatingstructures, respectively, and are operatively connected to said centerportion, such that when the first and second actuating parts deform inresponse to the electrical signal, the center portion of thecorresponding mirror layer tilts while remaining planar.
 2. The actuatedmirror array of claim 1, wherein the first and second actuating parts ineach of the actuating structures are of a bimorph structure and includesa first electrode, a second electrode, an intermediate metal layer, anupper motion-inducing thin film layer and a lower motion-inducing thinfilm layer, wherein the upper and lower motion-inducing thin film layersis separated by the intermediate metal layer, the first electrode isplaced on top of the upper motion-inducing thin film layer and thesecond electrode is placed below the lower motion-inducing thin filmlayer.
 3. The actuated mirror array of claim 2, wherein the upper andlower motion-inducing thin film layers are made of a piezoelectricmaterial.
 4. The actuated mirror array of claim 3, wherein thepiezoelectric material of the upper motion-inducing thin film layer ispoled in a direction opposite that of the lower motion-inducing thinfilm layer.
 5. The actuated mirror array of claim 1, wherein themotion-inducing thin film layer is selected from the group consisting ofa piezoelectric ceramic and a piezoelectric polymer.
 6. The actuatedmirror array of claim 5, wherein the motion-inducing thin film layer ispoled.
 7. The actuated mirror array of claim 1, wherein themotion-inducing thin film layer is made of an electrostrictive material.8. The actuated mirror array of claim 1, wherein the motion-inducingthin film layer is made of a magnetostrictive material.
 9. The actuatedmirror array of claim 1, wherein the first and second electrodes covercompletely the top and bottom surfaces of the motion-inducing thin filmlayer, respectively.
 10. The actuated mirror array of claim 1, whereineither the first or the second electrode covers partially the top or thebottom surface of the motion-inducing thin film layer.
 11. An array ofM×N thin film actuated mirrors for use in an optical projection system,the array comprising:an active matrix including a substrate and an arrayof M×N connecting terminals; an array of M×N thin film actuatingstructures, each of the actuating structures including a first and asecond actuating parts, the first and second actuating parts beingidentically structured, each of the first and second actuating partsbeing provided with a proximal and a distal ends, each of the first andsecond actuating parts having at least a thin film layer of amotion-inducing material, an elastic layer, and a first and a secondelectrodes, the elastic layer being placed at a bottom of themotion-inducing thin film layer, the first and second electrodes beinglocated on top of the motion-inducing thin film layer and bottom of theelastic layer, respectively, wherein an electrical signal applied acrossthe motion-inducing thin film and elastic layers between the first andsecond electrode causes a deformation thereof, and hence the actuatingpart; an array of M×N supporting members, each of the supporting membersbeing used for holding each of the actuating structures in place andalso for electrically connecting each of the actuating structures withthe active matrix; and an array of M×N mirror layers for reflectinglight beams, each of the mirror layers including a first side portion, asecond opposing side portion and a center portion located therebetween,said first side portion having a first side edge remote from said centerportion and a second side edge adjacent a respective side edge of saidcenter portion, said second opposing side portion having a first sideedge remote from said center portion and a second side edge adjacent arespective side edge of said center portion, wherein the first sideportion and the second opposing side portion of each of the mirrorlayers are secured on top of the first and second actuating parts ofeach of the actuating structures, respectively, and are operativelyconnected to said center portion, such that when the first and secondactuating parts in each of the actuating structures deform in responseto the electrical signal, the center portion of the corresponding mirrorlayer tilts while remaining planar.
 12. The actuated mirror array ofclaim 11, wherein the motion-inducing thin film layer and the elasticlayers are made of structurally similar materials.
 13. The actuatedmirror array of claim 12, wherein the elastic layer, made of aperovskite, is characterized by a high dielectric constant(.di-electcons.) and a low piezoelectric constant(d).
 14. The actuated mirrorarray of claim 11, wherein the motion-inducing thin film layer is madeof a perovskite.
 15. The actuated mirror array of claim 11, wherein thefirst electrode is made of a light reflecting material, thereby allowingthe first electrode to function also as the mirror layer.
 16. Theactuated mirror array of claim 11, wherein the first and secondactuating parts are cantilevered from each of the supporting members andwherein each of the supporting members is provided with a conduit forelectrically connecting each of the actuating structures with the activematrix.